No injuries were reported when the 50-foot long, 15-foot wide hole suddenly developed late Friday afternoon on Sinatra Drive, between 12th and 14th streets.
But the incident has disrupted travel in the waterfront area, and engineers say a slight further collapse there is still possible.
City spokesman Juan Melli says the cause of the collapse and how long repairs will take probably won't be known until at least Tuesday. Officials have said the work would likely take two to four weeks, but they note that site inspections are still ongoing.
The collapse area has been secured with fencing and barriers.